Axiom Home Page Forums General Discussion Stereo Adding a pre-amp to an AVR

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The Marantz doesn't have direct stereo

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Maybe I'm misunderstanding what you're trying to accomplish, but my SR5200 (two models down and one year behind) certainly has a direct stereo mode. Select your input and choose "S-Direct".

Thanks for the replies DJS and Ajax. I haven't seen any sonograms of different violins, but DJS if you can post some I'd like to see them. Ajax, I agree there is subtle complexity to violins - I really do think there's a difference you can hear between Strads and Taiwanese knock-offs. I also think the different designs, signal path length, capacitors, resistors, transistors, transformers, sound different. Folks upgrade capacitors in amps with audible results. Do these differences show up in sonograms? I think the proposition that all solid state amps sound the same is based on many assumptions including the assumption that the individual components which make up the amp do not have any audible effect on the sound. If all capacitors, resistors, transistors, transformers, circuit designs sound the same, then I suppose you could say all solid state amps with the same power output will sound the same at any given output. I just don't believe it. I'm not a actually a scientist but I did stay in a Holiday Inn and I'm open to letting my ears fool me. Sure sounds like upgrading components change the sound.

Do audio engineers measure all there is to measure about sound? Are our ears connected to more sophisticated sound analyzing software than a microphone generating 'sonograms'?

You're right, dmn (lol). I didn't notice because there's no button on the remote, only on the receiver. Thing is, I didn't detect anything different between s. direct and stereo mode. But with the latter, you can opt to have a sub. Thanks.

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haven't seen any sonograms of different violins, but DJS if you can post some I'd like to see them.

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Here you go 2x6. While not a true sonogram, it is close. It shows a way to track string motion via a laser sensor which basically does almost the same thing that a sonogram would do. Here is a page dedicated to sonograms and spectograms, but there are no pictures of violin sonograms within. Obviously I don't have any comparison sonograms between different types of violins because people buy the violin that sounds and looks good. They do not buy the violin that has a nice looking graph. This is due to the fact that there is no right or wrong with a violin. The characteristic sound of any particular violin is not "incorrect" as there is no reference to judge what is accurate. With an amplifier, there DEFINITELY is a right or wrong. The signal input is the end-all be-all reference point. A perfect amplifier will output exactly what is inputted with the sole exception of modulation of amplitude. "Right" is having a very linear power output throughout its rated bandwidth, power levels, and with different impedance loads. "Right" is having as low of a THD as possible and having a perfect square wave, sine wave, and triangle wave response when tested at different levels and under different loads.

I have to make one thing clear: I am not one to say that all amplifiers sound identical. Experience has shown me otherwise. I have an old reveiver (a 200W per channel stereo monster from the early 90s) that sounds different from my Pioneer 1014. It has a slightly overemphasized bass output and a sort of rolled-off, smooth treble. While I believe that there can be differences, I am a firm believer that if there ARE differences in amplifiers, they WILL show up with in-depth tests.

Just to show that I am not a pure "meter man," I do not hold the same views regarding loudspeakers because I feel that it is impossible to fully measure the output of a speaker in a 4-pi chamber in all directions with the temporal resolution needed to characterize a speaker as sounding a certain way. Plus, there are so many additional things to take into consideration with speakers such as resonance intensities around ports and if there are multiple ports how they affect eachother when their waves interact. This is not even taking a listening room into account which will further complicate the situation because due to differences in phasing as a result of crossovers, some speakers will by definition be harder to place in rooms than others.

In summary, my opinion on the matter is as follows:
Can there be differences in the sound of amps? YES, by all means. I have never stated otherwise.

If there are differences, will they show up in measurements? Yes.

Should there be differences in the sound of amps?
If they are competently designed solid state amps that have no coloration placed intentionally by the manufacturer, have ample power and are not strained during the test, no.

I hope that I have explained what I believe in an understandable manner.

Thank you DJ for your thoughtful response. Seems to me that matching the inupt and output of a single frequency test signal or a even a sweep does not necessarily correlate to very complex waveforms like music which would probably be much more difficult to test.

Typically a full bandwidth signal (pink noise for a logarithmic scale chart and white noise for a linear scale chart) is used. No serious review site uses sweeps. This would take ridiculously long to do (since to get a high resolution plot you need many, many points). These are undoubtedly more complex than music, I would assume, though I have no proof other than it simply having output at more frequencies at the same time than music. I see and respect the logic behind your arguement, but because pink noise is used instead of single frequencies, I believe it does not apply in this situation. Also please be aware that since all frequencies are used, there will be differences in phase as a function of time due to the different frequencies having constructive and destructive interference with eachother. That would prevent the amplifier from having an "easier" job with a full bandwidth signal compared to a test tone or music.